Here's another idea that i'm
stealing borrowing from /d/. Come up with a sexual fantasy that you would inflict on one or both sexes around the world. An example of this would be something like "All women now have weak bladders. Schools and workplaces are no longer required by law to have a women's bathroom".
Ejaculation is now an important bodily need for both sexes. Abstinence is no longer possible with willpower since there is now a physical limit to how much cum the human body can hold. Cum is produced at a constant rate and most people can only last a few days without sex or masturbation.
After just half a day, a person will be in a constant state of arousal until she cums. She will find most people sexually attractive, think about sex constantly, and will want to masturbate SO bad. This would be the time for a quick fap, but some people are not able to find a private place to do so. It gets worse, like a full bladder, and by the second day almost any sexual partner will do. The 300 pound WoW gamer who never showers? Total stud in the eyes of girls! That mean girl you hate? Sex goddess! It gets to the point where some people would just tackle and start dry humping the nearest stranger they can find just to get some relief. Finally, if you somehow resist sex and masturbation until the third day, you cum in your pants. Even in public, even if it's crowded, even without touching yourself, you dump a gallon of cum into your pants and moan orgasmically while people point and laugh.
One funny consequence of this is seeing people masturbating furiously in public because they couldn't hold it anymore. You may also walk into bathrooms and closets just to find couples humping like maniacs.
Another thing is the end of abstinence only education in schools. Telling your student no sex before marriage would make about as much sense as telling her to cross her legs and hold her bladder until her honeymoon.
All people who still say sex is wrong or sinful are mocked without mercy.